Lorem ipsum is placeholder text used to help designers avoid wasting their time on pages where they are inserting custom content.
It is Latin. It comes from the book by Cicero written in 45 BC. The name of this book is de Finibus Bonorum et Malorum (means "The Extremes of Good and Evil")
Lorem Ipsum means ‘pain itself’. It comes from Dolorem Ipsum.
It is now an industry-standard dummy text for designers, publishers, etc. When you don't know what text will fill the space you designed, you can just paste a lorem ipsum passage there.